Fusion draw processes are used in glass manufacturing operations to produce thin glass sheets that are used in a variety of products including flat panel displays. Glass sheets produced according to these processes typically exhibit enhanced flatness and smoothness compared to glass produced by different methods, such as the float method.
In order to produce glass ribbon in a draw process, pulling forces are applied to the glass ribbon in the direction of the draw via contact rollers while the glass is in a visco-elastic state. The glass ribbon is drawn by rollers which apply the pulling forces to stretch the glass ribbon in a draw direction (i.e., in a direction of glass travel) and in a cross-draw direction normal to the draw direction. The pulling forces process the glass to the desired thickness for use in commercial goods.
The physical interface of the rollers with the glass ribbon affects the stability of the glass ribbon during the draw process and affects the attributes of finished glass articles produced from the glass ribbon. In particular, the normal (pinch) force and normal force variation applied across the thickness of the glass ribbon by opposing rollers may affect glass attributes. Friction in the system used to manage the pinch force between opposing rollers reduces the effective normal force applied to the glass ribbon, and may lead to periodic and/or random variation in the force applied to the glass ribbon. Reduction in pinch force variation may reduce glass ribbon tension and reduce glass ribbon non-uniformity.
Accordingly, roller pairs and draw apparatuses incorporating roller pairs having alternative pinch force management systems are desired.